Ion implantation method

ABSTRACT

A method of tuning an ion implantation apparatus is disclosed. The method includes operations of applying any wafer acceptance test (WAT) recipe to a test sample, calculating a recipe for a direct current (DC) final energy magnet (FEM), calculating a real energy of the DC FEM, verifying the tool energy shift, and obtaining a peak spectrum of the DC FEM.

CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to U.S. Provisional Application62/712,802 filed on Jul. 31, 2018, the entire contents of which are andincorporated herein by reference.

BACKGROUND

Material properties can be changed, adjusted, or tuned by injecting orimplanting an extra species into the material. For example,semiconductors such as silicon can be changed to have higherconductivity by implanting an ion into the silicon. Ion implantationapparatus or ion implanters are widely used for doping (i.e. implantingan ion into) semiconductor wafers with at least one desired species ofions.

Ion implantation depth of wafers by an ion implanter is directlydependent upon the energy of the implanting ion in an ion beam.Therefore, accuracy in achieving desired implantation depth requiresaccurate control, measurement and monitoring of the energy of theimplanting ion. A direct current (DC) final energy magnet (FEM) is usedto control the energy of the implanting ion by controlling the strengthof the magnetic field. The magnetic field with a tuned magnetic fieldstrength causes the selected ions to travel in an accurate path with aparticular momentum.

Unfortunately, calibration of the DC FEM by measuring the energy shifttakes at least 12 hours. Thus, there is a demand for a more efficientmethod of calibration of the DC FEM.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 shows a top plan view of an ion implanter, according to anembodiment of the present disclosure.

FIG. 2 shows a top plan view of an ion implanter, according to anotherembodiment of the present disclosure.

FIG. 3 shows a graph of tool (x-axis) versus energy E (y-axis),indicating variation of energy ΔE obtained from the final energy magnet(FEM) of various ion implanters (i.e. tools A, B, C, D, E, and F),according to some embodiments of the present disclosure.

FIG. 4 shows a graph of applied magnetic field B (x-axis) versus energyE (y-axis), indicating variation of energy ΔE, according to someembodiments of the present disclosure.

FIG. 5 shows a flow chart of operations for calibration of the FEM,according to an embodiment of the present disclosure.

FIG. 6 shows a flow chart of operations for calibration of the FEM,according to another embodiment of the present disclosure.

FIG. 7 shows a graph of applied magnetic field B (x-axis) versus energyE (y-axis), indicating variation of energy ΔE after carrying out theoperations of FIG. 5 or FIG. 6, according to some embodiments of thepresent disclosure.

FIG. 8 shows a calibration unit of the FEM, according to an embodimentof the present disclosure.

FIG. 9 shows a calibration unit of the FEM, according to anotherembodiment of the present disclosure.

FIG. 10 shows a computer hardware diagram of an ion implantationapparatus, according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the invention. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“being made of” may mean either “comprising” or “consisting of.” In thepresent disclosure, a phrase “one of A, B and C” means “A, B and/or C”(A, B, C, A and B, A and C, B and C, or A, B and C), and does not meanone element from A, one element from B and one element from C, unlessotherwise described.

An ion implantation apparatus or an ion implanter is used to implant atleast a species of ion into a material to change the physical propertyof the material. For example, boron is implanted into silicon to changeits electrical property by making the boron doped silicon moreconductive such that a p-n junction or a transistor can be made for acomplicated circuit of a device. Calibration of an ion implanterrequires changing gas cylinders for providing different species of ionsfor acquiring sufficient number of data points for different ion massesand performing vacuum experiments to obtain sufficient number of datapoints for plotting a calibration curve. Thus, calibration of an ionimplanter requires at least 12 hours. During the data taking for thecalibration of the ion implanter, the production process has to becompletely stopped. Therefore, an efficient method or apparatus fortuning the ion implanter is demanded, especially when there are morethan one ion planters to be tuned.

FIG. 1 shows a top plan view of an ion implanter, according to anembodiment of the present disclosure. The ion implanter in FIG. 1 isused for medium current type, high current type, and high energy typeion implantations, according to some embodiments of the presentdisclosure. Medium energy current type ion implantations are mainly usedfor formation of channels, channel stoppers, and wells. High currenttype ion implantations are mainly used for formation of sources anddrains of transistors or contacts of a device. High energy type ionimplantations are mainly used for formation of deep wells andphotodiodes. The ion implanter in FIG. 1 is a batch wafer type ionimplanter, according to some embodiments of the present disclosure. Theion implanter includes a user interface 100 for inputting the parametersand viewing the data obtained by the ion implanter, according to someembodiments of the present disclosure. The user interface 100 includes awired or wireless desktop computer, a notebook computer, a tablet, asmartphone, and a remote control device, according to some embodimentsof the present disclosure. The user interface 100 includes a display forviewing the data obtained by the ion implanter and for inputting oradjusting parameters of the ion implanter, according to some embodimentsof the present disclosure. The display includes a cathode ray tube (CRT)display, liquid crystal display (LCD), light emitting diode (LED),organic light emitting diode (OLED) display, plasma display, and opticalprojector such as light-bulb projector or laser projection, according tosome embodiments of the present disclosure. The user interface 100includes a data input device, according to some embodiments of thepresent disclosure. The data input device includes a keyboard, voicecommand input microphone, iris scanning device, and a facial recognitiondevice, according to some embodiments of the present disclosure. Thedata input device also includes a cursor control device including amouse, a touch pad, and a touch screen, according to some embodiments ofthe present disclosure. The data input device of the user interface isconnected to the user interface through electrical wires or wirelessly,according to some embodiments of the present disclosure.

The ion implanter further includes an ion source loading chamber 110 forproviding ion source materials for the ion implanter, according to someembodiments of the present disclosure. The ion source material is loadedby opening the chamber 110 and placed on a container 130, according tosome embodiments of the present disclosure. The container 130 includes acrucible, according to some embodiments of the present disclosure. Also,the container 130 includes a heater (not shown) for evaporation of theion source material, according to some embodiments of the presentdisclosure. The container 130 containing a loaded ion source material ismoved through a transition tunnel 120 between the external environmentand the internal environment of the ion implantation chamber 160,according to some embodiments of the present disclosure. Then, thecontainer 130 containing the ion source material is positioned insidethe arc chamber 140 in which ions for the implanter are formed byheating the ion source material in the container 130 and applying avoltage to an extraction electrode 150 to extract the required ions forthe ion implanter, according to some embodiments of the presentdisclosure.

The generated ion stream passes into a region covered by magnetic fieldlines of an analyzer magnet 170 and the analyzer magnet 170 selects theappropriate ions based on the desired ion mass and charge by applyingand adjusting a magnetic field (and thus by Lorentz force), according tosome embodiments of the present disclosure. Only the ions having thedesired ion mass and charge can pass into the quadrupole lens (Q lens)region 180, according to some embodiments of the present disclosure. Theion stream then passes into a region surrounded by scanning electrode190, according to some embodiments of the present disclosure. Thescanning electrode 190 uses electrostatic method to uniformly scan theion beam in a frequency of 100 kHz throughout the area of each of thewafers. The scanning pattern of the scanning electrode 190 depends onthe desired outcome of the ion implanted wafers. The scanning electrode190 includes at least a pair of horizontal electrodes for controllingthe horizontal scanning and at least a pair of vertical electrodes forcontrolling the vertical scanning.

Then the ion stream passes into a region covered by parallel lens 200,according to some embodiments of the present disclosure. The Q lensregion 180 and the parallel lens 200 function to shape the ion beam,according to some embodiments of the present disclosure. The scanningelectrode 190 functions to scan the ion beam to cover the entire waferwidth of the wafer W1, according to some embodiments of the presentdisclosure.

The ion beam then passes into a region surrounded by anacceleration/deceleration column 210 for adjusting the speed of the ionbeam, according to some embodiments of the present disclosure. Then, theion beam passes into a region covered the magnetic field lines of afinal energy magnet (FEM) 220, according to some embodiments of thepresent disclosure. The FEM 220 functions to adjust the energy of theions for ion implantation into the wafer W1 located on a rotating disk240 inside a sample chamber 230, according to some embodiments of thepresent disclosure. The wafers located on the rotating disk 240 arerotated at a speed so as to allow all the wafers including wafer W2 toface the ions incoming from the FEM 220, according to some embodimentsof the present disclosure. If the ion beam misses the wafers androtation disk 240, the ion beam may continue to pass to impact on beamstopper 250.

The wafers on the rotation disk 240, e.g. W1 and W2, are loaded on acontainer (not shown) in a wafer loading chamber 280. Then, the wafer iscarried through a transition tunnel 270 between the external environmentof the ion implanter and the internal environment of the ion implanter.The transition tunnel 270 includes a valve or door (not shown) forprevention of contamination, according to some embodiments of thepresent disclosure. The wafers are then carried into a wafer chamber 230and are loaded onto the rotating disk 240 by a robotic arm 260,according to some embodiments of the present disclosure. The rotatingdisk 240 does not rotate when the wafers are loaded onto the rotatingdisk 240, according to some embodiments of the present disclosure.

FIG. 2 shows a top plan view of an ion implanter, according to anotherembodiment of the present disclosure. FIG. 2 shows a top plan view of anion implanter, according to an embodiment of the present disclosure. Theion implanter in FIG. 2 is used for medium current type, high currenttype, and high energy type ion implantations, according to someembodiments of the present disclosure. Medium energy current type ionimplantations are mainly used for formation of channels, channelstoppers, and wells. High current type ion implantations are mainly usedfor formation of sources and drains of transistors or contacts of adevice. High energy type ion implantations are mainly used for formationof deep wells and photodiodes. The ion implanter in FIG. 2 is a batchwafer type ion implanter, according to some embodiments of the presentdisclosure. The ion implanter includes a user interface 100 forinputting the parameters and viewing the data obtained by the ionimplanter, according to some embodiments of the present disclosure. Theuser interface 100 includes a wired or wireless desktop computer, anotebook computer, a tablet, a smartphone, and a remote control device,according to some embodiments of the present disclosure. The userinterface 100 includes a display for viewing the data obtained by theion implanter and for inputting or adjusting parameters of the ionimplanter, according to some embodiments of the present disclosure. Thedisplay includes a cathode ray tube (CRT) display, liquid crystaldisplay (LCD), light emitting diode (LED), organic light emitting diode(OLED) display, plasma display, and optical projector such as light-bulbprojector or laser projection, according to some embodiments of thepresent disclosure. The user interface 100 includes a data input device,according to some embodiments of the present disclosure. The data inputdevice includes a keyboard, voice command input microphone, irisscanning device, and a facial recognition device, according to someembodiments of the present disclosure. The data input device alsoincludes a cursor control device including a mouse, a touch pad, and atouch screen, according to some embodiments of the present disclosure.The data input device of the user interface is connected to the userinterface through electrical wires or wirelessly, according to someembodiments of the present disclosure.

The ion implanter further includes an ion source loading chamber 110 forproviding ion source materials for the ion implanter, according to someembodiments of the present disclosure. The ion source material is loadedby opening the chamber 110 and placed on a container 130, according tosome embodiments of the present disclosure. The container 130 includes acrucible, according to some embodiments of the present disclosure. Also,the container 130 includes a heater (not shown) for evaporation of theion source material, according to some embodiments of the presentdisclosure. The container 130 containing a loaded ion source material ismoved through a transition tunnel 120 between the external environmentand the internal environment of the ion implantation chamber 160,according to some embodiments of the present disclosure. Then, thecontainer 130 containing the ion source material is positioned insidethe arc chamber 140 in which ions for the implanter are formed byheating the ion source material in the container 130 and applying avoltage to an extraction electrode 150 to extract the required ions forthe ion implanter, according to some embodiments of the presentdisclosure.

The generated ion stream passes into a region covered by magnetic fieldlines of an analyzer magnet 170 and the analyzer magnet 170 selects theappropriate ions based on the desired ion mass and charge by applyingand adjusting a magnetic field (and thus by Lorentz force), according tosome embodiments of the present disclosure. Only the ions having thedesired ion mass and charge can pass into the quadrupole lens (Q lens)region 180, according to some embodiments of the present disclosure. Theion stream then passes into a region surrounded by scanning electrode190, according to some embodiments of the present disclosure. Thescanning electrode 190 uses electrostatic method to uniformly scan theion beam in a frequency of 100 kHz throughout the area of each of thewafers. The scanning pattern of the scanning electrode 190 depends onthe desired outcome of the ion implanted wafers. The scanning electrode190 includes at least a pair of horizontal electrodes for controllingthe horizontal scanning and at least a pair of vertical electrodes forcontrolling the vertical scanning.

Then the ion stream passes into a region covered by parallel lens 200,according to some embodiments of the present disclosure. The Q lensregion 180 and the parallel lens 200 function to shape the ion beam,according to some embodiments of the present disclosure. The scanningelectrode 190 functions to scan the ion beam to cover the entire waferwidth of the wafer W, according to some embodiments of the presentdisclosure.

The ion beam then passes into a region surrounded by anacceleration/deceleration column 210 for adjusting the speed of the ionbeam, according to some embodiments of the present disclosure. Then, theion beam passes into a region covered the magnetic field lines of afinal energy magnet (FEM) 220, according to some embodiments of thepresent disclosure. The FEM 220 functions to adjust the energy of theions for ion implantation into the wafer W located inside a samplechamber 230, according to some embodiments of the present disclosure.The position of the wafer W is maintained during the ion implantation,according to some embodiments of the present disclosure. If the ion beammisses the wafer W may continue to pass to impact on beam stopper 250.

The wafer W is located on a container (not shown) in a wafer loadingchamber 280. Then, the wafer is carried through a transition tunnel 270between the external environment of the ion implanter and the internalenvironment of the ion implanter. The transition tunnel 270 includes avalve or door (not shown) for prevention of contamination, according tosome embodiments of the present disclosure. The wafers are then carriedinto a wafer chamber 230 by a robotic arm 260, according to someembodiments of the present disclosure.

FIG. 3 shows a graph of tool (x-axis) versus energy E (y-axis),indicating variation of energy ΔE obtained from the final energy magnet(FEM) of various ion implanters (i.e. tools A, B, C, D, E, and F),according to some embodiments of the present disclosure. FIG. 3 showsthe energy data points measured for various ion implanters (i.e. toolsA, B, C, D, E, and F). For each of the tools, e.g. tool A, numerous datapoints are taken and the error bars are averaged values over the datapoints, indicating the energy shift ΔE of less than 2%. Tools B, C, D,E, and F have energy shift ΔE greater than 2%. Only tool A is measuredto have energy shift ΔE less than 2%. For an ion implanter to properlyfunction to produce accurate products, the energy shift ΔE is preferablyto be less than 2%. For an energy shift ΔE larger than 2%, the depth ofthe ion implantation and the dose cannot be accurately controlled andthe products produced by the ion implanter would be defective or havingquality deviated from the quality desired by customers.

When a user applies a magnetic field in the FEM 220, the user inputs theparameters to achieve the desired energy based on the equation of ionelectromagnetic rigidity p, i.e.

ρ=Br  Eq. (1)

where B is the applied magnetic field and r is the radius of trajectoryof the ion beam. The generated magnetic field B is always not the sameas the desired applied magnetic field. Therefore, a shift of magneticfield ΔB occurs. This shift of magnetic field ΔB causes the generatedmagnetic field from the FEM 220 to be different from the desired appliedmagnetic field and the energy of the ions outgoing from the FEM 220would not be the same as the desired value. Thus, an energy shift ΔEoccurs. This energy shift ΔE is required to be corrected so as toachieve an accurate energy value of the implanted ions.

FIG. 4 shows a graph of applied magnetic field B (x axis) versus ionenergy E (y axis). In the graph, a calibration curve is shown and thecurve indicates the relationship between the measured magnetic field Bby a magnetic field probe positioned at the central region of the FEM220 and the ion energy E obtained by measuring the radius of curvature rof the ion trajectory and the implanted depth and coverage, according tosome embodiments of the present disclosure. When a user operates an ionimplanter, the user inputs the parameters to control the appliedmagnetic field at a value at point 410 and expects to obtain the desiredimplantation energy 420. However, the actual applied magnetic fieldmeasured by a magnetic field probe positioned at the central region ofthe FEM 220 is a value at point 430 due to an energy shift ΔE and theion energy is thus lowered to point 440. Therefore, it may be necessaryto control the energy of the ions to have an energy shift ΔE less than2% and one of the methods to control the energy is by controlling theFEM 220, according to some embodiments of the present disclosure.

FIG. 5 shows a sequential process for calibrating the ion implantationapparatus, according to an embodiment of the present disclosure. It isunderstood that additional operations can be provided before, during,and after processes shown by FIG. 5, and some of the operationsdescribed below can be replaced or eliminated, for additionalembodiments of the method. The order of the operations/processes may beinterchangeable.

FIG. 5 shows a flow chart of operations of a method for calibration ofthe FEM 220, according to an embodiment of the present disclosure. Inthe method, an operation S510 is carried out to apply a wafer acceptancetest (WAT) recipe to test the sample wafer W1 after a test run of ionimplantation, according to some embodiments of the present disclosure.The purpose of the WAT is to determine the ion trajectory radius,implantation coverage, and the actually applied magnetic fieldB_(actual), according to some embodiments of the present disclosure. Theactually applied magnetic field B_(actual) can be used to determine theactual ion energy E_(actual), according to some embodiments of thepresent disclosure. With the values of the ion trajectory radius,implantation coverage, and the actually applied magnetic fieldB_(actual) determined, operation S520 is carried out to calculate the DCrecipe, i.e. the nominal parameters of the DC FEM 220 in the event ofion implantation of the sample W1 subjected to WAT, according to someembodiments of the present disclosure. Based on the calculated DCrecipe, the nominal applied magnetic field B_(nominal) is calculated. Inthis way, the nominal ion energy E_(nominal) is calculated. Then, anoperation S530 is carried out to calculate the actual ion energyE_(actual) based on the results of the WAT of the sample wafer W1, e.g.the actually applied magnetic field B_(actual). Then, an operation S540is carried out to verify the tool energy shift ΔE (i.e.|E_(actual)−E_(nominal)|). Then, an operation S550 is carried out totune the ion implantation apparatus using the tool energy shift ΔE.Then, an operation S560 is carried out to obtain the spectrum of the DCFEM 220.

FIG. 6 shows a sequential process for calibrating the ion implantationapparatus, according to an embodiment of the present disclosure. It isunderstood that additional operations can be provided before, during,and after processes shown by FIG. 6, and some of the operationsdescribed below can be replaced or eliminated, for additionalembodiments of the method. The order of the operations/processes may beinterchangeable. FIG. 6 shows a flow chart of operations of a method forcalibration of the FEM 220, according to an embodiment of the presentdisclosure. In the method, a calibration curve (with ion energy E beingthe y axis and the applied magnetic field B being the x axis) isobtained in an operation S610, according to some embodiments of thepresent disclosure. The operation is carried out by running testimplantation using various species of gas of different ion masses, e.g.boron and xenon. The actually applied magnetic field B is measuredmagnetic field probe positioned at the central region of the FEM 220,according to some embodiments of the present disclosure. The actual ionenergy E is measured by examining sample wafers during the test runs ofthe ion implantation. Then, an operation S620 is carried out to apply aservo loop to adjust the FEM 220 based on the calibration curve obtainedin the operation S610. Then, a test run on a sample wafer W1 is obtainedand an operation S630 is carried out to apply an acceptance test (WAT)recipe to test the sample wafer W1 after a test run of ion implantation,according to some embodiments of the present disclosure. The purpose ofthe WAT is to determine the ion trajectory radius, implantationcoverage, and the actually applied magnetic field B_(actual), accordingto some embodiments of the present disclosure. The actually appliedmagnetic field B_(actual) can be used to determine the actual ion energyE_(actual), for example, using the calibration curve obtained from theoperation S610, according to some embodiments of the present disclosure.With the values of the ion trajectory radius, implantation coverage, andthe actually applied magnetic field B_(actual) determined, operationS640 is carried out to calculate the DC recipe, i.e. the nominalparameters of the DC FEM 220 in the event of ion implantation of thesample W1 subjected to WAT, according to some embodiments of the presentdisclosure. Based on the calculated DC recipe, the nominal appliedmagnetic field B_(nominal) is calculated. In this way, the nominal ionenergy E_(nominal) is calculated, for example, using the calibrationcurve obtained from the operation S610. Then, an operation S650 iscarried out to calculate the actual ion energy E_(actual) based on theresults of the WAT of the sample wafer W1, e.g. the actually appliedmagnetic field B_(actual). Then, an operation S660 is carried out toverify the tool energy shift ΔE (i.e. |E_(actual)−E_(nominal)|). Then,an operation S670 is carried out to tune the ion implantation apparatususing the tool energy shift ΔE. Then, an operation S680 is carried outto obtain the spectrum of the DC FEM 220.

FIG. 7 shows a graph of applied magnetic field B (x axis) versus ionenergy E (y axis) after the operations of FIG. 5 or FIG. 6. In thegraph, a calibration curve of applied magnetic field B (x axis) versusion energy E (y axis) is shown and the curve indicates the relationshipbetween the applied magnetic field B by a magnetic field probepositioned at the central region of the FEM 220 and the ion energy Eobtained by measuring the radius of curvature r of the ion trajectoryand the implanted depth and coverage, according to some embodiments ofthe present disclosure. When a user operates the tuned ion implanter,the user inputs the parameters to control the applied magnetic field ata value at point 710 and expects to obtain the desired implantationenergy 720. In the ion implanter tuned by using the operations of FIG. 5or 6, the actual applied magnetic field measured by a magnetic fieldprobe positioned at the central region of the FEM 220 is a value atpoint 720 due to the fact that the energy shift ΔE becomes nearly zeroor less than 2% and the ion energy is thus not lowered and is at point720. Therefore, through operations of FIG. 5 or 6, the ion implanted istuned to have an energy shift ΔE less than 2% and the tuned ionimplanter produces accurate product with controllable ion implantationdepth and dose.

FIG. 8 shows a calibration unit of the FEM 220, according to someembodiments of the present disclosure. In FIG. 8, a wafer acceptancetest (WAT) instrument 810 is operated to test the wafer W1 to obtain theradius of trajectory of the ion beam, ion implantation coverage, and ionimplantation depth. The WAT instrument 810 is a hardware machine to testthe sample wafer W1 by using optical or tunneling electron method tomeasure the ion implantation depth, estimated implantation energy,radius of trajectory of ions, etc., according to some embodiments of thepresent disclosure. The WAT instrument 810 calculates the appliedmagnetic field using Eq. (1) based on the radius of trajectory and theion electromagnetic rigidity, according to some embodiments of thepresent disclosure. Then, the data resulted from the WAT instrument 810is transferred to a DC real energy calculator 830 to calculate theactual ion energy, according to some embodiments of the presentdisclosure. In some embodiments, the DC real energy calculator 830includes a calibration curve. The DC real energy calculator 830 includeshardware component such as processor for performing the function ofcalculation, according to some embodiments of the present disclosure.Then, the data resulted from the DC real energy calculator 830 aretransferred to the tool energy shift verifier 840, according to someembodiments of the present disclosure. A DC recipe calculator 820functions to perform calculation of nominal applied magnetic field basedon the parameters inputted to the ion implanter by the user, accordingto some embodiments of the present disclosure. The DC recipe calculator820 includes hardware component such as processor for performing thefunction of calculation, according to some embodiments of the presentdisclosure. Then, the data resulted from the DC recipe calculator 820are transferred to the tool energy shift verifier 840, according to someembodiments of the present disclosure. The tool energy shift verifier840 then calculates the energy shift based on the results obtained fromthe DC recipe calculator 820 and DC real energy calculator 830,according to some embodiments of the present disclosure. Then, the toolenergy shift verifier 840 outputs result to the ion implantationapparatus tuning unit 850 which tune the parameters of the ion implanterby, for example, increase/decrease the parameters inputted by the userafter the user inputs the parameters, according to some embodiments ofthe present disclosure. Then, ion implantation apparatus tuning unit 850outputs the results to the DC FEM spectrum generator 860 to generate aspectrum of FEM 220. The magnetic spectrum of the FEM 220 accuratelyadjusts the ion energy to the user-desired value.

FIG. 9 shows a calibration unit of the FEM 220, according to someembodiments of the present disclosure. In FIG. 9, a calibration curveobtaining unit 910 functions to obtain a calibration curve of appliedmagnetic field (x axis) versus ion energy (y axis). The calibrationcurve obtaining unit 910 functions to run test implantation usingvarious species of gas of different ion masses, e.g. boron and xenon.The calibration curve obtaining unit 910 includes hardware componentsuch as a magnetic field probe and a processor. The actually appliedmagnetic field B is measured magnetic field probe positioned at thecentral region of the FEM 220, according to some embodiments of thepresent disclosure. The actual ion energy E is measured by examiningsample wafers during the test runs of the ion implantation. Thecalibration curve obtaining unit 910 then outputs the result to servoloop unit 920. The servo loop unit 920 functions to adjust the FEM 220using a servo loop to adjust the parameters based on the calibrationcurve obtained from the calibration curve obtaining unit 910. The servoloop unit 920 includes hardware component such as processor to controlthe parameters of the FEM 220. The servo loop unit 920 then outputs thecalibration curve and the parameters obtained from the servo loopoperation to a wafer acceptance test (WAT) instrument 930. The units andoperations 930-980 of FIG. 9 are the same as or similar to the units andoperations 810-860 of FIG. 8. The WAT instrument 930930 is operated totest the wafer W1 to obtain the radius of trajectory of the ion beam,ion implantation coverage, and ion implantation depth. The WATinstrument 930 is a hardware machine to test the sample wafer W1 byusing optical or tunneling electron method to measure the ionimplantation depth, estimated implantation energy, radius of trajectoryof ions, etc., according to some embodiments of the present disclosure.The WAT instrument 930 calculates the applied magnetic field using Eq.(1) based on the radius of trajectory and the ion electromagneticrigidity, according to some embodiments of the present disclosure. Then,the data resulted from the WAT instrument 930 is transferred to the DCreal energy calculator 950 to calculate the actual ion energy, accordingto some embodiments of the present disclosure. In some embodiments, theDC real energy calculator 950 includes a calibration curve. The DC realenergy calculator 950 includes hardware component such as processor forperforming the function of calculation, according to some embodiments ofthe present disclosure. Then, the data resulted from the DC real energycalculator 950 are transferred to the tool energy shift verifier 960,according to some embodiments of the present disclosure. A DC recipecalculator 940 functions to perform calculation of nominal appliedmagnetic field based on the parameters inputted to the ion implanter bythe user, according to some embodiments of the present disclosure. TheDC recipe calculator 940 includes hardware component such as processorfor performing the function of calculation, according to someembodiments of the present disclosure. Then, the data resulted from theDC recipe calculator 940 are transferred to the tool energy shiftverifier 960, according to some embodiments of the present disclosure.The tool energy shift verifier 960 then calculates the energy shiftbased on the results obtained from the DC recipe calculator 940 and DCreal energy calculator 950, according to some embodiments of the presentdisclosure. Then, the tool energy shift verifier 960 outputs result tothe ion implantation apparatus tuning unit 970 which tune the parametersof the ion implanter by, for example, increase/decrease the parametersinputted by the user after the user inputs the parameters, according tosome embodiments of the present disclosure. Then, ion implantationapparatus tuning unit 970 outputs the results to the DC FEM spectrumgenerator 980 to generate a spectrum of FEM 220. The magnetic spectrumof the FEM 220 accurately adjusts the ion energy to the user-desiredvalue.

FIG. 10 shows a computer hardware diagram of an ion implantationapparatus, according to some embodiments of the present disclosure. Asschematically shown in FIG. 10, a generic computer of the ion implanter,e.g. the computer 100 (FIGS. 1 and 2), includes several functional unitsconnected in parallel to a data communication bus 1010, for example ofthe PCI type. In particular, a Central Processing Unit (CPU) 1020,typically comprising a microprocessor, controls the operation of thecomputer 100, a working memory 1030, typically a RAM (Random AccessMemory) is directly exploited by the CPU 1020 for the execution ofprograms and for temporary storage of data, and a Read Only Memory (ROM)1040 stores a basic program for the bootstrap of the computer 100. Thecomputer 100 comprises several peripheral units, connected to the bus1010 by means of respective interfaces. Particularly, the peripheralunits that allow the interaction with a human user are provided, such asa display device 1050 (for example a cathode ray tube (CRT), a liquidcrystal display (LCD), a light emitting diode (LED) display, an organiclight emitting diode (OLED) display, or a plasma monitor), a keyboard1060 and a pointing device 1070 (for example a mouse or a trackpoint).The computer 100 also includes peripheral units for local mass-storageof programs (operating system, application programs) and data, such asone or more magnetic Hard-Disk Drivers (HDD) 1080 driving magnetic harddisks, a memory card reader 1090, and a CD-ROM/DVD driver 2000, or aCD-ROM/DVD juke-box, for reading/writing CD-ROMs/DVDs. Other peripheralunits may be present, such as a floppy-disk driver for reading/writingfloppy disks, a memory card reader for reading/writing memory cards andthe like. The computer 100 is further equipped with a Network InterfaceAdapter (NIA) card 2100 for the connection to the data communicationnetwork 2200 such as internet; alternatively, the computer 100 may beconnected to the data communication network 2200 by means of a MODEM.

The system, method, computer program product, and propagated signaldescribed in the present disclosure may, of course, be embodied inhardware; e.g., within or coupled to a Central Processing Unit (“CPU”),microprocessor, microcontroller, System on Chip (“SOC”), or any otherprogrammable device. Additionally, the system, method, computer programproduct, and propagated signal may be embodied in software (e.g.,computer readable code, program code, instructions and/or data disposedin any form, such as source, object or machine language) disposed, forexample, in a computer usable (e.g., readable) medium configured tostore the software. Such software enables the function, fabrication,modeling, simulation, description and/or testing of the apparatus andprocesses described herein. For example, this can be accomplishedthrough the use of general programming languages (e.g., C, C++), GDSIIdatabases, hardware description languages (HDL) including Verilog HDL,VHDL, AHDL (Altera HDL) and so on, or other available programs,databases, nanoprocessing, and/or circuit (i.e., schematic) capturetools. Such software can be disposed in any known computer usable mediumincluding semiconductor, magnetic disk, optical disc (e.g., CD-ROM,DVD-ROM, etc.) and as a computer data signal embodied in a computerusable (e.g., readable) transmission medium (e.g., carrier wave or anyother medium including digital, optical, or analog-based medium). Assuch, the software can be transmitted over communication networksincluding the Internet and intranets. A system, method, computer programproduct, and propagated signal embodied in software may be included in asemiconductor intellectual property core (e.g., embodied in HDL) andtransformed to hardware in the production of integrated circuits.Additionally, a system, method, computer program product, and propagatedsignal as described herein may be embodied as a combination of hardwareand software.

Any suitable programming language can be used to implement the routinesof the present invention including C, C++, Java, assembly language, etc.Different programming techniques can be employed such as procedural orobject oriented. The routines can execute on a single processing deviceor multiple processors. Although the steps, operations or computationsmay be presented in a specific order, this order may be changed indifferent embodiments. In some embodiments, multiple steps shown assequential in this specification can be performed at the same time. Thesequence of operations described herein can be interrupted, suspended,or otherwise controlled by another process, such as an operating system,kernel, etc. The routines can operate in an operating system environmentor as stand-alone routines occupying all, or a substantial part, of thesystem processing.

In the description herein, numerous specific details are provided, suchas examples of components and/or methods, to provide a thoroughunderstanding of embodiments of the present invention. One skilled inthe relevant art will recognize, however, that an embodiment of theinvention can be practiced without one or more of the specific details,or with other apparatus, systems, assemblies, methods, components,materials, parts, and/or the like. In other instances, well-knownstructures, materials, or operations are not specifically shown ordescribed in detail to avoid obscuring aspects of embodiments of thepresent invention.

A “computer-readable medium” for purposes of embodiments of the presentinvention may be any medium that can contain, store, communicate,propagate, or transport the program for use by or in connection with theinstruction execution system, apparatus, system or device. The computerreadable medium can be, by way of example only but not by limitation, anelectronic, magnetic, optical, electromagnetic, infrared, orsemiconductor system, apparatus, system, device, propagation medium, orcomputer memory.

A “processor” or “process” includes any human, hardware and/or softwaresystem, mechanism or component that processes data, signals or otherinformation. A processor can include a system with a general-purposecentral processing unit, multiple processing units, dedicated circuitryfor achieving functionality, or other systems. Processing need not belimited to a geographic location, or have temporal limitations. Forexample, a processor can perform its functions in “real time,”“offline,” in a “batch mode,” etc. Portions of processing can beperformed at different times and at different locations, by different(or the same) processing systems.

Reference throughout this specification to “one embodiment”, “anembodiment”, or “a specific embodiment” means that a particular feature,structure, or characteristic described in connection with the embodimentis included in at least one embodiment of the present invention and notnecessarily in all embodiments. Thus, respective appearances of thephrases “in one embodiment”, “in an embodiment”, or “in a specificembodiment” in various places throughout this specification are notnecessarily referring to the same embodiment. Furthermore, theparticular features, structures, or characteristics of any specificembodiment of the present invention may be combined in any suitablemanner with one or more other embodiments. It is to be understood thatother variations and modifications of the embodiments of the presentinvention described and illustrated herein are possible in light of theteachings herein and are to be considered as part of the spirit andscope of the present invention.

Embodiments of the invention may be implemented by using a programmedgeneral purpose digital computer, by using application specificintegrated circuits, programmable logic devices, field programmable gatearrays, optical, chemical, biological, quantum or nanoengineeredsystems, components and mechanisms may be used. In general, thefunctions of the present invention can be achieved by any means as isknown in the art. Distributed, or networked systems, components andcircuits can be used.

Communication, or transfer, of data may be wired, wireless, or by anyother means.

It will also be appreciated that one or more of the elements depicted inthe drawings/figures can also be implemented in a more separated orintegrated manner, or even removed or rendered as inoperable in certaincases, as is useful in accordance with a particular application.

It is also within the spirit and scope of the present invention toimplement a program or code that can be stored in a machine-readablemedium to permit a computer to perform any of the methods describedabove.

Additionally, any signal arrows in the drawings/Figures should beconsidered only as exemplary, and not limiting, unless otherwisespecifically noted. Furthermore, the term “or” as used herein isgenerally intended to mean “and/or” unless otherwise indicated.

Combinations of components or steps will also be considered as beingnoted, where terminology is foreseen as rendering the ability toseparate or combine is unclear.

As used in the description herein and throughout the claims that follow,“a”, “an”, and “the” includes plural references unless the contextclearly dictates otherwise. Also, as used in the description herein andthroughout the claims that follow, the meaning of “in” includes “in” and“on” unless the context clearly dictates otherwise.

Using the above mentioned methods, e.g. in FIGS. 5 and 6, thecalibration of the FEM 220 involves mostly computer calculation withoutthe need to change gas cylinders for performing numerous laboriousexperiments to obtain a graph of calibration curve. The calibrationmethods thus reduce the time needed for calibration of ion implantationapparatus, especially when there are numerous ion implantation apparatusthat needed to be calibrated.

It will be understood that not all advantages have been necessarilydiscussed herein, no particular advantage is required for allembodiments or examples, and other embodiments or examples may offerdifferent advantages.

According to some embodiments of the present disclosure, a method oftuning an ion implantation apparatus is disclosed. The method includesan operation of applying a wafer acceptance test (WAT) recipe to a testsample. An operation of calculating a recipe for a direct current (DC)final energy magnet (FEM). An operation of calculating a real energy ofthe DC FEM. An operation of verifying a tool energy shift. An operationof tuning the ion implantation apparatus based on the verified toolenergy shift. An operation of obtaining a magnetic spectrum of the DCFEM. The method further includes an operation of obtaining a calibrationcurve of the DC FEM. The method further includes an operation ofperforming servo loop to adjust parameters of the DC FEM. The recipe forthe DC FEM includes an applied magnetic field. The tool energy shift isverified by calculating a difference between a nominal energy and thereal energy. The nominal energy is obtained by calculating a nominalapplied magnetic field. The nominal applied magnetic field is calculatedbased on parameters entered by a user. The real energy is obtained bycalculating an actual applied magnetic field by data obtained from theprocess of applying the WAT recipe to a test sample.

According to some embodiments of the present disclosure, a method oftuning a final energy magnet (FEM) is disclosed. The method includes anoperation of obtaining a calibration curve of the DC FEM. An operationof performing servo loop to adjust parameters of the DC FEM. Anoperation of applying a wafer acceptance test (WAT) recipe to a testsample. An operation of calculating a recipe for a direct current (DC)final energy magnet (FEM). An operation of calculating a real energy ofthe DC FEM. An operation of verifying a tool energy shift. An operationof tuning the DC FEM based on the verified tool energy shift. Anoperation of obtaining a peak spectrum of the DC FEM. The recipe for theDC FEM includes an applied magnetic field. The tool energy shift isverified by calculating a difference between a nominal energy and thereal energy. The nominal energy is obtained by calculating a nominalapplied magnetic field. The nominal applied magnetic field is calculatedbased on parameters entered by a user. The real energy is obtained bycalculating an actual applied magnetic field by data obtained from theprocess of applying the WAT recipe to a test sample.

According to some embodiments of the present disclosure, an ionimplantation system is disclosed. The system includes a sample platform,an ion gun, an electrostatic linear accelerator, and a direct current(DC) final energy magnet (FEM) tuned by operations of applying a waferacceptance test (WAT) recipe to a test sample on the sample platform,calculating a recipe for the DC FEM, calculating a real energy of the DCFEM, verifying a tool energy shift of the DC FEM, tuning the DC FEMbased on the verified tool energy shift, and obtaining a peak spectrumof the DC FEM. The system further includes that the DC FEM is tuned byobtaining a calibration curve of the DC FEM. Also, the system furtherincludes that the DC FEM is tuned by performing servo loop to adjustparameters of the DC FEM. The recipe for the DC FEM includes an appliedmagnetic field. The tool energy shift is verified by calculating adifference between a nominal energy and the real energy. The nominalenergy is obtained by calculating a nominal applied magnetic field.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method of tuning an ion implantation apparatus,comprising: applying a wafer acceptance test (WAT) recipe to a testsample; calculating a recipe for a direct current (DC) final energymagnet (FEM); calculating a real energy of the DC FEM; verifying a toolenergy shift; tuning the ion implantation apparatus based on theverified tool energy shift; and obtaining a magnetic spectrum of the DCFEM.
 2. The method of claim 1, further comprising: obtaining acalibration curve of the DC FEM.
 3. The method of claim 2, furthercomprising: performing servo loop to adjust parameters of the DC FEM. 4.The method of claim 1, wherein the recipe for the DC FEM includes anapplied magnetic field.
 5. The method of claim 1, wherein the toolenergy shift is verified by calculating a difference between a nominalenergy and the real energy.
 6. The method of claim 5, wherein thenominal energy is obtained by calculating a nominal applied magneticfield.
 7. The method of claim 6, wherein the nominal applied magneticfield is calculated based on parameters entered by a user.
 8. The methodof claim 5, wherein the real energy is obtained by calculating an actualapplied magnetic field by data obtained from the process of applying theWAT recipe to a test sample.
 9. A method of tuning a final energy magnet(FEM), comprising: obtaining a calibration curve of the DC FEM.performing servo loop to adjust parameters of the DC FEM applying awafer acceptance test (WAT) recipe to a test sample; calculating arecipe for a direct current (DC) final energy magnet (FEM); calculatinga real energy of the DC FEM; verifying a tool energy shift; tuning theDC FEM based on the verified tool energy shift; and obtaining a peakspectrum of the DC FEM.
 10. The method of claim 9, wherein the recipefor the DC FEM includes an applied magnetic field.
 11. The method ofclaim 9, wherein the tool energy shift is verified by calculating adifference between a nominal energy and the real energy.
 12. The methodof claim 11, wherein the nominal energy is obtained by calculating anominal applied magnetic field.
 13. The method of claim 12, wherein thenominal applied magnetic field is calculated based on parameters enteredby a user.
 14. The method of claim 11, wherein the real energy isobtained by calculating an actual applied magnetic field by dataobtained from the process of applying the WAT recipe to a test sample.15. An ion implantation system comprising: a sample platform, an iongun, an electrostatic linear accelerator, and a direct current (DC)final energy magnet (FEM) tuned by: applying a wafer acceptance test(WAT) recipe to a test sample on the sample platform; calculating arecipe for the DC FEM; calculating a real energy of the DC FEM;verifying a tool energy shift of the DC FEM; tuning the DC FEM based onthe verified tool energy shift; and obtaining a peak spectrum of the DCFEM.
 16. The ion implantation system of claim 15, further comprising:the DC FEM is tuned by obtaining a calibration curve of the DC FEM. 17.The ion implantation system of claim 16, further comprising: the DC FEMis tuned by performing servo loop to adjust parameters of the DC FEM.18. The ion implantation system of claim 15, wherein the recipe for theDC FEM includes an applied magnetic field.
 19. The ion implantationsystem of claim 15, wherein the tool energy shift is verified bycalculating a difference between a nominal energy and the real energy.20. The ion implantation system of claim 15, wherein the nominal energyis obtained by calculating a nominal applied magnetic field.